Covers are applied to surfaces for reasons which are dependent on the nature of these surfaces. Thus, in the case of a basin such as a swimming pool the cover may prevent contamination with leaves or by animals, may allow savings on energy, water and reagents, and may or must afford the safety of individuals and in particular children. In the case of a desalination basin or basin used for other fluid treatments, a cover makes it possible to avoid the liquid becoming diluted with rainwater or excessive evaporation due to heat.
In the case of a sports ground such as an outdoor grass-court or clay-court tennis court, a cover affords protection against inclement weather, and in particular intermittent rain. Moreover, a vehicle body is covered notably to ensure that the loads remain stable in the depression caused by the movement of the vehicle and to protect same against inclement weather. Covers are also used as blinds for greenhouses, conservatories or vehicle windows in order to prevent any overheating inside, and as sunscreens for patio awnings.
In all instances, the search is generally for a covering device that is economic allowing easy, dependable, repeatable and quick covering and uncovering, requiring a minimum of human intervention, and above all, having the longest life possible. Numerous devices for covering a surface have been developed, ranging from basic models to more sophisticated ones. Such devices are described for example in WO2014068131.
One advantageous type of covering device comprises a motorized drum mounted on a longitudinal-translation mechanism. This mechanism moves the drum over the surface that is to be covered, literally allowing the cover to be “laid” on the surface, as it deploys, by unrolling it from the drum simultaneously with the longitudinal movement thereof, and then lifted off, as it is removed, by simultaneously rolling it up on the drum. The cover therefore does not slide over the surface either when it is being deployed or when it is being removed. The covering device also comprises a system for securing the covering to one transverse end of the surface that is to be covered so that the translational and rotational movements of the drum cause the cover to be unrolled or rolled up over the surface that is to be covered.
In the present application, the terms “longitudinal” “transverse” and derivatives thereof refer respectively to the direction of travel of the drum and to the direction of the axis of revolution thereof.
There are such covering devices that allow the longitudinal edges of the covering to be secured as the covering is being deployed and, in some instances to apply transverse tension to said covering in order to tension it perfectly. Such devices are described in WO2010/010152, WO2010/054960 and Belgian patent application BE2012/0725. In these devices, the longitudinal edges of the cover are provided with a rod or bead which is introduced into the upward-facing opening of a U-section rail with one or two flanges partially closing said opening. The bead slipping under a flange and being held in this position by suitable securing means allows the longitudinal edges of the cover to be secured firmly.
As described in WO2010010152 and WO2014064138, the bead in such covers is typically formed as a projection on a free exterior edge of a longitudinal strip which is secured to each longitudinal edge of the cover at the interior edge thereof, opposite to the exterior edge. However, it has been found in several instances, particularly in outdoor applications and/or swimming pool covers, that the longitudinal strips and the beads thereof very rapidly degrade and need to be changed after excessively short intervals of time. It is clear that, as a cover is deployed and removed, the longitudinal strips and the beads thereof are exposed to harsh abrasion loadings and that the material used needs to be chosen with care. Despite a careful choice of materials that exhibit high abrasion resistance, the problem of accelerated degradation of the longitudinal strips and of their bead remains.
The present invention proposes a solution to the accelerated degradation of the longitudinal strips and beads thereof which is observed in serval devices used to cover a surface with a cover, the longitudinal edges of which are secured.